Mixed-metal coordination networks constructed from Hg(CN)2 rods and Hg⋯Naz (az = azide) secondary interactions: Syntheses and structures of Hg(CN)2·(N3)2·Cu(C5H5N)2 and NaHg(CN)2·(N3)2·Cu(N3)(C3H10N2)2

► New coordination networks containing rod-like ligands. ► Mercury secondary bonding interactions. ► Jahn-Teller distortions. ► Layered structures.